Officials said biologists found just 28 bats in a survey of places where they hibernate for the winter. Two formerly common species were missing.

"White-nose syndrome has decimated little brown bats and northern long-eared bats," said New Hampshire Fish and Game biologist Emily Preston. "Little brown bats were the most common species in the state before 2009."

White-nose syndrome is a fungal infection that infects bats during the winter while they are hibernating. It damages the thin tissue of the wing that helps regulate their temperature.

"Since bats are hibernating, their immune system is suppressed, so they cannot fight the fungus," Preston said.

The fungus causes the bats to wake up from hibernation more frequently, and they burn through their fat stores faster. They then often don't have enough stored fat to survive the winter.

White-nose syndrome was first found in New Hampshire in 2009. A survey this winter found that a mine that had 514 bats in 2009 now had no bats.

"I can't believe we've lost so many bats, so quickly," said researcher Jacques Veilleux. "I had some small hope that we might see a bit of a recovery this year. It's sad that we have experienced a near complete loss of our wintering bats and really sad to think I likely won't be around to witness a possible recovery of these populations."

Experts said bats typically have one pup per year, so it could take decades for the population to rebound, if it does.

Overall, more than 90 percent of little brown and northern long-eared bats in the Northeast have been killed by the disease, which has spread to 23 states and five Canadian provinces.

The researchers said even though they didn't find any little brown or northern long-eared bats hibernating, they may not be gone from the state. New Hampshire's summer bats also fly to Vermont and New York to hibernate.

"We monitor a couple of little brown bat maternity colonies. These are places where female bats raise their pups," Preston said. "So far, these still have bats, and they are producing pups."

Homeowners can also help monitor bat populations by surveying the number of bats in colonies in homes and barns. Under a citizen science program run by the Fish and Game Department, homeowners go out at dusk and count the number of bats that exit the colony when it gets dark.